exhaust valve acting funny

[Magice]

my engine is running poor / backfiring and i noticed that the exhaust valve pops twice before the intake valve. The exhaust valve opens, closes, half opens, closes, intake opens etc

any ideas whats gone wrong.. its a gx340

 

[Jerryburger]

I believe you've won the "What the Heck is Going On With My Engine?!?" contest! Make sure and pull the spark plug for easier hand- spinning, and then VERIFY that:
1.) Spin the crank slowly forward...You should get (EXHAUST open/close) and then immediately afterward, (INTAKE open/close) and these events should take place every other complete turn of the crank. If it's not doing that, open the valve cover on top of the head and verify that the rockers are where they belong. Maybe one has slipped off of it's pivot and is actuating the other valve somehow, causing the double-tap. I've never pulled one of these motors apart yet, but that might be it. I had a Cadillac 425 rocker kinda slip off it's pivot, and similar things happened.

 

[Jerryburger]

OR... (BrainFart Mechanism Activated) does the GX340 have some sort of compression release? Maybe that's outta whack. I'll look it up.

 

[Magice]

I popped the cylinder head and the push rod pushers do the same thing.. exhaust out exhaust in exhaust half out exhaust in intake out intake in repeat

 

[gocartkid]

Wow....I'm kinda stumped. My only suggestion is to look in the case to see if there is any foreign object in there (or on the cam??) that would be activating the pushrod.

 

[Magice]

alright theres something weird on the cam.. is it easy to put the cam back in if i pull it?

 

[oscaryu1]

Honda and Clones both have compression release... unless you specify for an aftermarket cam not to have one.

But I'm sticking to stuck valve. Take off the valve cover and look at it while you spin the flywheel.

 

[2or3wheels]

i bet your compression releace it screwed up take it apart and take a look inside.

 

[oscaryu1]

Compression release is on backside of cam. New cams are around $20 at www.gxparts.com

 

[I like karts]

some kind of honda style easy spin??


Its kind of the same on briggs flatheads exept it's the intake valve